Could you add scaled-down battlecruiser hulls to the CA hulls from 1910-1920? There's no use for armoured cruisers in that period and you would just make the smallest BC hull and fit some small guns to make a bunch of cheap, fast, BCs that approximate what CAs do.
I know that IRL CAs weren't built after 1910 or so, but in Rule the Waves 3, I usually have a lighter contingent of CAs that have speeds that can accompany BCs but have less tonnage than BCs. I can't do that in this game as all CAs have a max hull form of 23 knots or so, which is less than a BC of 29 knots.